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TECHNICAL PAPERS: Gas Turbines: Coal, Biomass, and Alternative Fuels

# A Technoeconomic Analysis of Different Options for Cogenerating Power in Hydrogen Plants Based on Natural Gas Reforming

[+] Author and Article Information

Dipartimento di Ingegneria Industriale, Università di Perugia, Via G. Duranti 93, 06125 Perugia, Italy

Umberto Desideri

Dipartimento di Ingegneria Industriale, Università di Perugia, Via G. Duranti 93, 06125 Perugia, Italyumberto.desideri@unipg.it

Change in ST load can affect steam extraction to SMR, but off-design analysis is not an argument of the present paper.

In the REF plant and in all GT cycles, steam is exported at $27bar$ and $550°C$; thus, its enthalpy content is $3.5GJ∕t$. In REF, HC and LC saturated steam at $27bar$ is produced, equivalent to $2.7GJ∕t$.

J. Eng. Gas Turbines Power 129(2), 338-351 (Aug 10, 2006) (14 pages) doi:10.1115/1.2434346 History: Received June 13, 2006; Revised August 10, 2006

## Abstract

Steam methane reforming is the most common process for producing hydrogen in the world. It currently represents the most efficient and mature technology for this purpose. However, because of the high investment costs, this technology is only convenient for large sizes. Furthermore, the cooling of syngas and flue gas produce a great amount of excess steam, which is usually transferred outside the process, for heating purposes or industrial applications. The opportunity of using this additional steam to generate electric power has been studied in this paper. In particular, different power plant schemes have been analyzed, including (i) a Rankine cycle, (ii) a gas turbine simple cycle, and (iii) a gas-steam combined cycle. These configurations have been investigated with the additional feature of $CO2$ capture and sequestration. The reference plant has been modeled according to state-of-the-art of commercial hydrogen plants: it includes a prereforming reactor, two shift reactors, and a pressure swing adsorption unit for hydrogen purification. The plant has a conversion efficiency of $∼75%$ and produces $145,000Sm3∕hr$ of hydrogen (equivalent to $435MW$ on the lower-heating-volume basis) and $63t∕hr$ of superheated steam. The proposed power plants generate, respectively, $22MW$ (i), $36MW$ (ii), and $87MW$ (iii) without $CO2$ capture. A sensitivity analysis was carried out to determine the optimum size for each configuration and to investigate the influence of some parameters, such as electricity, natural gas, and steam costs.

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## Figures

Figure 1

Scheme of the reference hydrogen plant

Figure 2

Scheme of SMR in SC plant

Figure 3

Scheme of SMR in GT plant

Figure 4

Scheme of SMR in CC plant

Figure 5

Simplified scheme of the main streams and blocks and gas composition for plants with CO2 capture

Figure 6

CoH in function of NG cost for a CoE of $0.05∕kWh (solid lines) and$0.06∕kWh (dotted lines)

Figure 8

PB period relative to the investment for power plant: CoE is fixed at $0.05∕kWh(a) and$0.06∕kWh(b). Steam-NG cost ratio is 1.1 (solid lines), 0.8 (dashed lines), and 0.5 (dotted lines).

Figure 9

PB period relative to the investment for power plant in function of NG cost: CoE=0.05∕4.7×NGcost ($/kWh); Steam-NG cost ratio is 1.1 (solid lines), 0.8 (dashed lines), and 0.5 (dotted lines) Figure 10 Influence of plant capacity on CoH for NG cost=$4.7∕GJ, CoE=$0.05∕kWh, steam/NG cost=1.1 Figure 11 Influence of plant capacity on CoH for NG cost=$4.7∕GJ, CoE=$0.05∕kWh, steam/NG cost=0.5 Figure 12 Influence of plant capacity on PB for NG cost=$4.7∕GJ. Steam/NG cost=1.1 (solid lines) and 0.5 (dotted lines). (a) CoE=$0.05∕kWh and (b) CoE=$0.06∕kWh.

Figure 13

Influence of NG cost on CoH in the REF plant, for a carbon tax of $20∕tCO2 (solid lines) and$40∕tCO2 (dotted lines)

Figure 14

Influence of Ctax on CoH (NG cost=$4.7∕GJ, CoE=$0.05∕kWh)

Figure 15

Influence of Ctax on PB in LC plants (NG cost=$4.7∕GJ, CoE=$0.05∕kWh)

Figure 16

Influence of Ctax on PB in HC and IC plants (NG cost=$4.7∕GJ, CoE=$0.05∕kWh)

Figure 7

CoH in function of cost ratio between steam and NG. Solid lines: NG=$4.7∕GJ; CoE=$0.05∕kWh and dotted lines: NG=$5.64∕GJ; CoE=$0.06∕kWh. Gray lines: NG=$6.58∕GJ; CoE=$0.07∕kWh.

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